Abstract: In a piezoelectric transformer, a piezoelectrically inactive region 11 is provided between a driving portion 22 and a power generating portion 31. The power generating portion 31 extends longitudinally of the piezoelectric body 1 and is provided with a pair of top and bottom electrodes 7T and 7B on its major surfaces. The driving portion 22 is provided with a side electrode 5 on a side surface perpendicular to the width direction. Other electrodes 50T and 50B are also provided so as to be parallel to the electrodes 7T and 7B. The power generating portion 31 is polarized in the width direction and the thickness direction of the piezoelectric body and the driving portion 22 is polarized in the width direction of the piezoelectric body 1. By regulating width of the piezoelectrically inactive region 11 provided between the electrode 50T (50B) of the driving portion 22 and the electrode 7T (7B) of the power generating portion 31, the transforming ratio can be regulated.

Abstract: A microwave tube collector assembly includes a metal cylinder and a chromium oxide film. The metal cylinder has at least a layer of a chromium alloy on its overall inner circumferential surface and is closed at one end thereof. The a chromium oxide film is formed on the basis of the chromium alloy to cover the inner circumferential surface of the metal cylinder.